For AI generation

Precise enough for humans. Constrained enough for agents.

Carrier’s advantage isn’t maximal language power. It’s that the backend surface is small, explicit, and compiler-checked. That is exactly the shape that lets code generators stay consistent across a project — and across drafts.

Why it fits

Five properties that matter

Narrow syntax

Fifteen top-level declarations. One service. A tight scalar set, arrays, optionals, enums, and record types. Fewer ways to be wrong.

Authoring tiers

Docs grade constructs: Tier 1 first-pass-safe, Tier 2 recommended, Tier 3 advanced runtime. Start at the smallest tier that fits.

First-class manifest

Every build emits .carrier/manifest.json: models, routes, policies, jobs, schedules, clients. Tools read it instead of scraping source.

Compiler feedback loop

carrier check runs the full semantic pass — types, CRUD validity, auth/policy rules, idempotency scope, built-in signatures.

Predictable layout

Numeric-prefixed multi-file layout (00_models, 10_types, 20_actions, 30_routes) keeps generation order stable.

Generated CRUD

crud replaces the repetitive hand-written endpoints that are most likely to drift between drafts.

Docs for agents

The generation recipe, verbatim from docs/ai-authoring.md

This is the order the AI authoring guide recommends. It matches what the compiler expects in practice.

docs/ai-authoring.md

fast generation recipe

1.  write  carrier.toml
2.  declare one  service
3.  add  auth jwt  if any route is protected
4.  create  enum   used by models or query defaults
5.  create  model  declarations
6.  create  type   declarations for I/O and pagination
7.  add  crud      for resource-like models
8.  add  policy    for role or tenant visibility
9.  add  action    for real business writes
10. add custom  route
11. add  job / event / schedule   only when needed
12. add  client    for outbound integrations
13. add pure  fn   helpers last

Tier 1 — first-pass-safe

one service · optional auth jwt · type · route · optional model + crud · pure fn helpers

Tier 2 — recommended

multi-file layout · action with transactions · idempotent write routes · policy where role visibility matters

Tier 3 — platform

cache · jobs · schedules · events · audit · raw SQL · DB functions · typed clients · @version · tenant RLS

Honest

What NOT to invent

Carrier is grounded, not aspirational. The AI authoring guide is explicit about what does not exist yet.

Language features not present in the repository — no trait system, no generics, no macros, no custom decorators, no package registry.

Framework magic — Carrier does not hide behavior behind annotations. Everything visible compiles into the expected output.

Selective imports — imports are validated metadata; every .carrier file under src/ compiles together.

return inside transaction { } — do the work in the block, return after.

Language reference →Examples